Flask for casting orthodontic study models



Sept 1 1970 R. C. ROHLFING 3,526,021

FLASK FOR CASTING ORTHODONTIC STUDY MDELS Filed Feb. 19, 1968 2 Sheets-Sheet 1 INVENTOR RAYMOND C. ROHLFING BYJLJXLLLN ATTO RNEY SePtl, 1970 R. c. RoHLFlNG 3,526,021

FLASK FOR CASTING ORTHODONTIC STUDY MODELS Filed Feb. 19, 1968 2 SheetS-Sheet 2 INVENTOR me@ u SYM@ ATTORNEY j RAYMOND c. ROHLFINv United States Patent O M 3,526,021 FLASK FOR CASTING ORTHODONTIC STUDY MODELS Raymond C. Rohling, Ortho-Tech Laboratories, Inc.,

5900 Hampton Ave., St. Louis, Mo. 63109 Filed Feb. 19, 1968, Ser. No. 706,321 Int. Cl. A61c 13/00 U.S. Cl. 18-33 5 Claims ABSTRACT OF THE DISCLOSURE A ask for casting orthodontic study models characterized by a xed wall extending upward from a ask base, with movable side walls having elements converging toward a plane extending transversely of the xed wall, and a movable end wall having divergent elements thereof closing against said converging elements, a dental impression tray adapted to be received in the polygonal area defined by said walls, and a gasket underlying said tray and having marginal portions extending around said tray and between said walls for trapping casting material poured into said ask.

The invention herein is directed to orthodontic study models which are accurate reproductions of the upper and lower dental arch. They are used as a diagnostic aid, and are made of white orthodontic plastic, and are finished to standard specifications known in the profession generally as -Ricketts or Tweed specifications.

Heretofore it has been generally difiicult to prepare good specimens having desired smooth reference faces free from voids in the casting process. It has also been necessary to perform many sawing and linishing operations to prepare an acceptable study model having proper reference planes free from void areas occasioned by occluded air in the casting material, these void areas having had to be corrected by tedious hand operations.

It is accordingly a principal object of this invention to provide an improved ask for casting orthodontic study models of various sizes, having in each instance the proper reference planes free from voids in the surfaces thereof, and also free from surface irregularities which result from heretofore known casting methods or apparatus.

Another object is to provide a ask capable of withstanding vibration during the casting process, and yet capable of being readily stripped from the study model cast there- 1n.

Still another object is to provide a flask capable of accommodating dental impression trays of various types and sizes, and to incorporate with such trays a yieldable gasket, so that during the pouring operation the casting material will be eectively retained, and iiow about the dental im.- pression and against the walls of the ask to provide a completely acceptable study model.

In the drawings:

FIG. l is a front elevation view of an improved fiask for casting orthodontic study models, said ask embodying the principles according to the present invention;

FIG. 2 is a plan view thereof;

FIG. 3 is a side elevation view looking in the direction of the arrows 3 3 of FIG. l;

FIG. 4 is an exploded perspective view showing the elements comprising the ask of FIGS. l to 3 together with a yieldable gasket and a dental impression tray adapted to be used therewith;

FIG. 5 is a plan view of a dental tray showing a dental impression supported thereon;

FIG. 6 is a plan view of the improved flask, showing the dental impression tray with impression thereon, positioned within the iiask, and ready for pouring of the casting material into the flask;

3,526,021 Patented Sept. 1,. 1970 FIG. 7 is a vertical section taken along the line 7-7 of FIG. 6 looking in the direction of the arrows;

FIG. 8 is a top plan view of an orthodontic study model prepared in the flask according to the present invention; and

FIG. 9 is a side elevational view of a completed study model comprised of a pair of castings made from upper and lower dental impressions.

Referring now to the drawings, the improved -il'ask according to the present invention is referred to generally by the reference numeral 1'0 and includes a base 11 having a front foot 12 and a rear foot 13 which is coterminous 'with a xed wall 14 extending upward fro-m the base 11.

Laterally opposed side walls 16 and 17 extend upward from the base 11 laterally from a plane A-A extending transversely to the wall 14. Each of the side walls 16 and 17 has a base foot 18 into which are tapped wing screws 19. These extend through slots 21 in the base 11, and comprise structure whereby the position of the side walls 16 and 17 may be adjusted with respect to the aforesaid reference plane.

The side walls 16 and 17 each have elements 22 which converge toward plane A-A and in a direction toward an end wall 23. The latter has a foot 24, and is adapted to move laterally of itself along the axis A-A to close the polygonal area described by the ixed wall 1.4 and the movable side walls 16 and 17. Foot 24 is secured in adjusted position to the base 11` by wing screws 26 extending through slots 27 in the base 11 and tapped into the foot 24.

End wall '23 has elements 28 diverging from the plane A-A, and the vertical edges 29 of the diverging elements 28 contact the convergent elements 22 of the side walls 16 and 17 when the flask 10 is assembled as seen particularly in FIGS. 2 and 6 to define a polygonal area having included angles at the apices thereof corresponding to those desired between the planes of a cast orthodontic study model.

The flask 10 is adapted to receive a dental impression tray 31 seen in FIG. 4. Such tray may be of any commercial available form and size, and may be provided with perforations 32 for the bedding of impression material placed thereon prior to insertion in a patients mouth. As is known, such material takes a permanent set in the patients mouth and is removed from the mouth together with the tray 31 by a short handle 33. The tray 31, together with the impression DI thereon, then has the appearance as seen in FIG. 5.

A gasket 34 made of yieldable material, such as certain kinds of wax or the like, is adapted to underlie the tray 31 and has contours corresponding to the contours of the tray 31. Gasket 34 is adapted to embrace the tray 31 along its sides and has a marginal rib 36 adapted to embrace the sides of the tray 31, and to close the area between the impression DI and the walls of the ask 10.

As seen in FIG. 4, the gasket 34 has an opening 37 through which the handle 33 of the impression tray 31 extends, so that the gasket 34 may be placed about the tray 31 in the manner described.

Preparatory to making a casting within the flask 10, the gasket 34 is placed about and under the tray 31 containing the dental impression DI. The end wall 23 is released from the base 11 by wing screws 26, and the tray and gasket supported on a ledge 38 supported on fixed wall 14 and extending inward of the same. Side walls 16 and 17 are likewise provided with ledges 39 extending inward of the same for such purpose. Movable end wall 2.3 has an opening 41 therein through which handle 33 extends when tray 31 and gasket 34 are supported on the ledges 38V and 39. IEnd wall 23 likewise has a ledge 42 on the inner face thereof for support of gasket 34.

In placingthe gasket 34, tray 31 and dental impression DI in the position seen in FIG. 7, the side walls 16v and 17 are loosened with respect to the base 11. End wall 23` is brought against the gasket 34 and tightened in position, and side walls 16 and 17 adjusted in position, so that the elements 22 thereof are brought against the ends 29 of elements 28 of wall 23. The gasket 34, being yieldable, then completely `lls the area between the impression DI and the inside of the walls of the flask.

The entire assembly is then placed on a suitable vibrating device, and the ask filled with casting 'material which has been mixed under sub-atmospheric pressure to remove occluded air therefrom. As seen in FIG. 7, the casting material, in the form of a wet, thick slurry, is poured into flask while the latter is vibrated. When properly -illed, the excess is struck oi at the topf of the flask, and the material permitted to take its set, The iinished casting, denoted by the letter C in FIGS. 8 and 9 are then sawn along the top and bottom faces. It may be noted in FIG. 9 that upper and lower study models are shown in their normal bite position, each such model having been made in the manner described.

I claim:

1. A flask for casting orthodontic study models comprising a base, a wall extending upward from said base, a pair of opposed side walls extending upward from said base, means for adjusting the position of said side walls laterally of each other, an end wall having the ends thereof closing against said side walls, means for adjusting the position of said end wall on said base, a dental impression tray adapted to be received in the polygonal area dened by the aforesaid walls, and a yieldable gasket underlying said tray and having marginal portions extending around said tray and between the aforesaid walls for traps ping casting material poured into said ask.

2. The iiask according to claim 1 wherein said side rwalls are adjusted to positions laterally of a plane extending transversely of said -iirst named wall, and are provided with elements thereof converging toward said plane and against said end wall.

3. The flask according to claim 1 wherein said end wall has elements diverging from said plane with the ends of said elements in contact with the con-verging elements of said side Walls.

4. The flask according to claim 1 wherein said first named wall and said side walls have ledges mounted on the inner faces thereof for supporting said gasket and said dental impression tray.

5. The ilask according to claim 1 wherein said dental impression tray has a handle extending therefrom, and wherein said end wall has an opening therein through which said handle extends.

References Cited UNITED STATES PATENTS 555,345 2/1896 Smallwood.

757,093 4/ 1904 Coltrin 249-169 1,477,091 12/ 1923 Von der Heydt lil- 34.1 1,834,980 12/1931 Stealy 18-34.1 1,961,609 6/1934- Gorder L 1'8-5.7 1,972,238 9/ 1934 Reilel 18-33 2,425,048 8/ 1947 Schlesinger 18-33 3,281,901 11/1966A Davis et al 18-34.1

J. HOWARD FLINT, JR., Primary Examiner U.S. Cl. XJR. 18-34.1 

